Her songs are all basically "We broke up and it was your fault/you were a jackass so I broke up with you" or some other way of calling a guy a jerk or saying it was his fault.

Nuh uh!! Totally not true!!!

Back to December was she apologising. Change was about beating the system. Ours is about being with someone even though her family disapproves. Fearless is just sweet, sweet, sweet. Long Live was about her touring. Love Story was also about being with someone other people disapproves. The Best Day was spending a day with her mum. You Belong With Me is her mooning over someone. Mine's about struggling with someone together. Mean was bashing her critics.

You and you anti-Taylor hate groups are too blinded by your prejudices to look at the facts!

Back to December was she apologising. Change was about beating the system. Ours is about being with someone even though her family disapproves. Fearless is just sweet, sweet, sweet. Long Live was about her touring. Love Story was also about being with someone other people disapproves. The Best Day was spending a day with her mum. You Belong With Me is her mooning over someone. Mine's about struggling with someone together. Mean was bashing her critics.

You and you anti-Taylor hate groups are too blinded by your prejudices to look at the facts!

Opinion and quality are different things. You can like a music or not. A music can be good or not. You can like a bad music or dislike a good music.

That is actually very well said, and true.
There is in fact a possibility to measure music on skill levels. How skilled an instrument is played. How many different instruments are played by a musician at high skills. How many octaves a singers voice spans. How intelligent, and complicated an arrangement of harmonies is written. And it all doesn't translate that just because it is of top quality level, that everyone likes it.
It's fairly safe to say, that almost all Pop-Music is a "throw away" article. There is not much skill involved. It's easy, slapped together samples and loops, to create some modern background sound to a song, and then some rather simple melody. It's aimed to sound catchy, to create sales. Then a random person with a semi-decent voice gets grabbed to appeal the target group, and gets pushed as a star. The real quality of a music artist only shows over decades of work in the field. If they can maintain their status, then they are that for a reason. And that reason is always higher skill than the throw-away product artists.
Yet it still has rather nothing to do with whether it's liked or not by someone.
Skill can be measured, and argued... Taste cannot.